Processes for scouring textiles

ABSTRACT

Textile fibers which have been desized and are about to be bleached are scoured with a boiling alkaline caustic solution containing a surfactant and a solubilizing agent such as amino tri(methylene phosphonic acid). This process provides fibers with a substantially reduced impurity level and an end product which is substantially more conducive to a subsequent dyeing process.

United States Patent Inventor Xavier Kowalski Creve Coeur, Mo.

App]. No. 854,358

Filed Aug. 27, 1969 Patented Nov. 2, 1971 Assignee Monsanto Company St. Louis, Mo.

PROCESSES FOR SCOURING TEXTILES Primary Examiner-Mayer Weinblatt Attorneys-Herbert B. Roberts, James J. Mullen and Neal E.

Willis ABSTRACT: Textile fibers which have been desized and are about to be bleached are scoured with a boiling alkaline caustic solution containing a surfactant and a solubilizing agent such as amino tri(methylene phosphonic acid). This process provides fibers with a substantially reduced impurity level and an end product which is substantially more conducive to a subsequent dyeing process.

PROCESSES FOR SCOURING TEXTILES The present invention relates to an improved process for bleaching and dyeing textile materials. Specifically, this invention is concerned with scouring materials with a composition containing an organic material which functions as a solubilizing agent.

Preparing textile materials for dyeing and finishing generally involves a series of well-known steps. The material is first singed to burn off excess fibers, desized to remove any artificial coating put. on the material for processing, rinsed, and then it is scoured. After scouring, the material is again rinsed and then, in succession, itis bleached, scoured, rinsed, mercerized, rinsed, dyed or printed, and finished. These steps are more specifically described in Chemistry and Chemical Technology of Cotton, lnterscience Publishers, Inc., New York, N. Y. 1955, edited by Kyle-Ward, Jr., and which is incorporated herein by reference. A discussion per se of the scouring step starts on Page 144 of said publication.

In general, scouring is the fourth major step in the abovedescribed textile finishing process. The purpose of the scouring step is to remove foreign matter left on the textile material after desizing. The foreign matter can be naturally occuring colorants, waxes, and protein, as on a cotton-fiber. The foreign matter can also be materials applied. to fibers and yarns to improve their manufacture into fabrics, as in weaving or knitting, but which have to be removed prior to dyeing and finishing to insure that the color of the material will be uniform throughout. These materials can besizes such as starch, polyvinyl alcohol, ethylene maleic anhydride, carboxy methyl cellulose and others, or lubricants such as emulsified oils, softeners, antistatic materials, and others.

The scouring process is desirable in order toattempt to remove impurities or foreign matter and thus ultimately. prepare a whiteness in color product suitable for .sub-

sequent dyeing and effectinga uniformity of color thereon. Generally, commercial scouring or boiling processes involve contacting the textile material with alkaline aqueoussolution containing a caustic material such as sodium hydroxide and a surfactant. in the past, however, this type of scouring stepwas not substantially completely effective in that the subsequently bleached textile material did notexhibit a better than fair whiteness in color. By the practice of the present invention, however, the whiteness of the bleached material is substantially improved.

Accordingly, it is an object of this invention to improve the process of the type described so as to enhance the appearance of the textile material treated and to clean the surface of said material to promote a more effective dyeing step.

Other objects will become apparent in view of the subsequent detailed description and appended claims. It has been unexpectedly found that-the above objects can be accomplished by including an amino tri(lower alkylidenephosphonic acid) or water-soluble salt thereof in the boiling aqueous alkaline scouring bath in addition to the causticmaterial and surfactant. The amino tri(lower alkylidene phosphonic acids) have the general formula:

present invention. The preferred salts are the sodium salts,

particularly the pentasodium salt. Other alkali metal salts, such as potassium, lithium and the like, as well as mixtures of the alkali metal salts may be used. In addition, any water-soluble salt, such as the ammonium salt, e.g.,

N[Cl-I,PO (NH,), (Cl-l PO l-lNl-h) and the amine salts,

2 s( a)2)2l2 (CHZPOSHN(CHB)R) which exhibit the characteristics of the alkali metal salt may be also used to practice the invention.

It is found-desirable to useat least about 0.01 percent by weight of said phosphonic acid based on the total weight of the combination of the caustic, surfactant, said phosphonic acid (or salt thereof,) and water. It is togbe understood that the amount necessary depends upon the level of contamination of the scouring bath. However, the general usage of the abovementioned amino phosphonic acids indicates a practical upper limit is about 2.0 percentby weight. The; preferred range is from about 0.1 percent to about 0.5-percent. e

The, temperature of the bath isdesirable in therange of from about 125 F. to the boiling point of the scouringsolution but temperaturesfrom about 140 F. to about 210 F. are preferred.

it is believed that the amino tri(lower alkylidene phosphonic acids) unexpectedly contribute to the scouring step by solubilizing (removing from the surface) the polymeric foreign materials on the fibers and thus speed up their emulsification, saponification, or hydrolysis by the caustic in solution whichgenerally is sodium hydroxide. This mechanism is quite unexpected, especially since the contribution of the abovementionedamino phosphonic acid to the removal of these foreign materials is greater than that of the surfactant. It is to be understood that the above idea or-mechanism is merely a'theory and is not intended to be limitative as to the scope of this invention.

The practice of the invention and the'advantages provided thereby ,are furtherillustrated by the following examples which arenotintended to be limitative:

EXAMPLE I One practical method to ascertain the degree of cleanliness of a textile, material is to determine its whiteness.'This can be accomplished by using a Gardner Automatic Color Difference Meter madejby Gardner Laboratory, Inc., Bethesday-Maryland. The colordifference meter directly measures color by reflectance indifferent scales. in this test, the color was determined relative to a standard which was as closetoperfect whiteness :as.-is possible. Utilizing this testing device, the machine is so calibrated that the control or-standardmaterial used for comparative purposes registers a b valueto zero. When a high positive b value is obtained, the material is too .yellow. A negative, b value indicates blueness. Inthe textile industry, itis desirable tohave as low a b value as possible, even if the material is on the blue (negative) side of the b scale. Too much blueness isundesirable, but it is acceptable up to a point because it means that the material has less impurities in it.

These impurities, thus, cause the yellow color.

As a practical demonstration, 1 liter of boiling caustic solution containing 80.0 grams of a 50 weight percentsodium hydroxide solution and 12.0 grams of =Biofax .-P-35, a phosphated surfactant typical of those used in the industry,

5 were usedin ,this'experimentas the scouring bath. Six-20 gram'fabric samples, two of 100 percentcotton, two of 35 percent cotton-and percentpolyestenand.two of 50 percent cotton and SOpercent polyester were tested..For.each kind of fabric, one-sample was scoured in the bath described above with the addition of 2.3 grams of amino tri(methylene phosphonic acid) herein referred to as ATMP, and one-sample was scoured without ATMP. Each samplewas scouredfor one hour at 210 -F..and rinsed twice with water at 2l0F.for 30 minutes each time. The results are shown in the following table I.

TABLE I "b" Value Fabric Without ATMP With ATMP I005: Cotton 7.5 6.4 35% Cotton. 65% Polyester -0.2 l.2 50% Cotton, 50% Polyester 6.8 4.8

The b value of the cotton fabric sample scoured with ATMP was 14.7 percent lower than the b value of the sample scoured without it. The b value of the 35 percent cotton and 65 percent polyester fabric was 600 percent lower when scoured with ATMP than when scoured without it. The b value of the 50 percent cotton and 50 percent polyester fabric was 29.4 percent lower with ATMP. All of the recorded b value differences (i.e., 1.1, L0, and 2.0) are significant since a 0.2 difference in b value is considered in the art as substantial. In fact, the color difference of 0.2 b value can readily be seen by visual observation.

EXAMPLE ll Another method to determine cleanliness of textiles is to determine the amount of water extractable and solvent extractable foreign matter left on the material after scouring. This is accomplished by extracting the foreign matter by rinsing the textile material with separate and individual portions of several different solvents and then finally, water. The rinse solution is then evaporated and the amount of foreign matter which was on the textile material is determined by weighing the residue. The solvents used in this experiment were trichloroethylene, ethanol and acetone, and then water.

The samples of 100 percent cotton fabric and 35 percent cotton and 65 percent polyester fabric from Example I were treated in the manner described above. Similar unscoured samples of those fabrics were also tested. The results are shown in the following table ll:

Extractables Cotton I: Solvent 0.30 0.22 0.84 Extractables 5 Water Extractables 35% Cotton, 0.50 0.43 6.36

65% Polyester Solvent 0.55 0.48 0.72

Extractables The higher the numerical value, the more foreign matter present on the phosphonic acid) with substantially the same results.

The foregoing examples have been described in this specification for the purpose of illustration and not limitation. Many other modifications and ramifications will naturally suggest themselves to those skilled in the art based on this disclosure. These are intended to be comprehended as within the scope of this invention.

What is claimed is:

1. In a process for treating textile materials which comprises the steps of singeing, desizing, scouring, bleaching. scouring, mercerizing, dyeing or printing, and finishing, the improvement which comprises incorporating into the scouring bath, which is maintained at a temperature of from about F. to about 210 F., which consists essentially of a caustic material and a surfactant, at least 0.01 percent by weight, based on the total weight of the scouring bath, of a solubilizing agent which is amino tri(methylene phosphonic acid).

2. The process as set forth in claim 1 wherein the concentration of the solubilizing agent is from about 0.1 to about 0.5 percent by weight.

3. The process as set forth in claim 1 wherein the caustic material is sodium hydroxide. 

2. The process as set forth in claim 1 wherein the concentration of the solubilizing agent is from about 0.1 to about 0.5 percent by weight.
 3. The process as set forth in claim 1 wherein the caustic material is sodium hydroxide. 